Building control systems are employed to regulate and control various environmental and safety aspects of commercial, industrial and residential facilities (hereinafter referred to as “buildings”). In ordinary single-family residences, control systems tend to be simple and largely unintegrated. However, in large buildings, building control systems often consist of multiple, integrated subsystems employing hundreds of elements.
For example, a heating, ventilation and air-conditioning (“HVAC”) building control system interrelates small, local control loops with larger control loops to coordinate the delivery of heat, vented air, and chilled air to various locations throughout a large building. Local control systems, for example, open and close vents that supply heated or chilled air based on local room temperature readings. Larger control loops, for example, obtain many distributed temperature readings and/or air flow readings to control the speed of a ventilation fan, or control the operation of heating or chilling equipment.
As a consequence of the interrelationship of these control loops, many elements of a building control system must communicate information to each other. To this end, communication networks have been incorporated that transmit digital data between and among the various elements in accordance with one or more sets of protocols.
Some of the core elements of a sophisticated building control system include field controller devices, supervisory control stations, plant equipment, sensors and actuators. Sensors and actuators constitute the terminal devices of the building control system. Sensors measure and/or collect raw data regarding the system, and actuators physically change the output of the system. Sensors may include, for example, temperature sensors, humidity sensors, air flow sensors and the like. Actuators may include, for example, devices that alter fan speed, alter the position of ventilation shaft dampers, or alter the flow of hot water through heating pipes.
Field controllers, sometimes referred to as field panels, are distributed control units that in large part control the operation of the system, at least in localized areas of the building. To this end, field panels or controllers may receive sensor signals from the sensors and provide control signals to one or more actuators. The field panel devices generate such control signals based on the sensor signals and other control signals. The other control signals can be set point values received from other field panel devices and/or the supervisory work station.
As is known in the art, a field controller is typically a wall-mounted housing that includes multiple I/O sockets or terminals for connecting to actuators, sensors and smaller subsystems. The field controller also includes processing circuitry and memory. The field controller processing circuitry runs firmware that is specially adapted to the physical configuration of the field panel. Various field panels of this type are commercially available. One such field panel or field controller or field controller is the MEC controller available from Siemens Building Technologies, Inc. of Buffalo Grove, Ill. Historically, field controllers are mounted on a wall near the location in which the sensors and actuators are installed.
The supervisory work station is typically a general purpose computer having a human user interface that allows for human technicians to monitor and control overall system operation. The supervisory work stations operate more as a data server that can access certain types of data from the field controllers, and allow user input of certain set points and control output values. The supervisory work stations typically include a computer work station host having at least the elements of an ordinary personal computer. An example of a building control system work station is the INSIGHT.™. brand work station available from Siemens Building Technologies, Inc. of Buffalo Grove, Ill.
In such building control systems, the field controller devices are generally connected to each other as well as to the one or more supervisory work stations in order to share information necessary for coherent building control.
The above described architecture is effective and has been widely implemented. However, this architecture has some drawbacks. One such drawback is that the field controllers can be difficult or at least inconvenient to test and demonstrate. Because of the specialized nature of the field controller hardware, an actual working field controller must be employed to demonstrate the functionality of the field controller and to test new functionalities of the field controller. Working field controllers are not always conveniently available.
There is a need, therefore, for a building control system that reduces the need for working field controllers for at least some limited uses.